<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Object</title>
</head>
<body>
    <script>
        var uname = 'jack';
        function change() {
            console.log(uname);
            var uname = 'lily';
            console.log(uname);
        }
        change();

        var length = 10;
        function fn() {
            alert(this.length);
        }
        var obj = {
            length: 5,
            method: function(fn) {
                fn(); // ?
                arguments[0](); // ?
            }
        }
        obj.method(fn);
    </script>
</body>
</html>